I. Field of the Invention
This invention relates to a water craft capable of efficiently reducing infestation in bodies of water by aquatic plants and the like.
II. Information Disclosure
Certain aquatic plants grow so prodigiously as to create a problem for other aquatic life forms and for navigation by man. There have been several attempts to produce water crafts which control such uncontrolled and harmful growth. Examples of such efforts are described in U.S. Pat. Nos. 3,469,377 ('377); 3,541,769 ('769); 3,611,680 ('680); 3,706,185 ('185); 3,866,396 ('396); 4,196,566 ('566); 4,520,616 ('616); 4,638,621 ('621); 4,616,588 ('588); 5,142,849 ('849); 5,110,311 ('311); 5,379,709 ('709).
The '377 patent describes a mower for harvesting seaweed. It is also suggested that waterhyacinth could be harvested using this apparatus. However, the principal use of this machine, regardless of the type of vegetation attacked, is to harvest rather than destroy.
The '769 patent relates to a diverter which can be attached to an aquatic harvester. This diverter is not a vehicle which itself can be used to clear waterways.
The '680 patent relates to a machine for harvesting vegetation from waterways comprising a raking means, a shredder means, and a means for disposing vegetation after it has been shredded. This machine is not designed so as to be able to clear large areas of water quickly.
The '185 patent describes an apparatus for removing marine growths and roots comprising injection of water and compressed air below the root system followed by removal of the plants.
The '396 patent describes a device for harvesting aquatic vegetation. The forward portion of the apparatus is equipped with a submerged rotating drum having cutting edges for cutting submerged plants. The cut plants are then sucked into an internal processing compartment where they are further cut and subsequently dried and packaged.
In the '566 patent, a water craft was described having two shafts projecting from the vehicle, with a circular cutting blade mounted at the distal end of each shaft such that the two blades interlock. The blades cut aquatic plants and their roots while at the same time operate as the sole means for propelling the vehicle forward.
The '616 patent describes a method and system for conditioning and removing aquatic plants. The problem of waterhyacinth infestation of waterways is noted in this patent and a solution thereto is suggested which comprises using a water craft having at least one rotatable drum to condition plants so as to be uniformly distributed across a body of water, followed by removal of the plants using a buoyant, flexible material to surround and reel in the plants. This method is slow and expensive, as the harvested plants have to be gathered and disposed of.
The '621 patent describes a method and system for processing aquatic plants comprising a shore mounted harvesting and chopper means, primarily for preparing animal feed.
The '588 patent describes a navigable water craft for removal of weeds from the beds of waterways. The craft is designed for small scale harvesting of, and not destruction of vegetation.
The '849 patent describes an aquatic plant cutting apparatus and aquatic plant recovery boat equipped with the apparatus. The apparatus comprises a submerged cutting means outside of a water craft equipped with the cutting means.
The '311 patent describes an air boat adapted to plow through slime- or plant-infested waters. The boat is not adapted to mulch vegetation.
The '709 patent describes an amphibious vehicle for cleaning swamps and marshlands. The vehicle has a pontoon hull and tracks. The vehicle is not adapted to rapid clearance of waterways infested with water-borne plant matter.
Other references are mentioned in several of these patents.
In general, known water craft for removal or processing of aquatic biomatter are slow vehicles, severely limited in the amount of acreage that can be cleared in a short amount of time. With quickly replicating plants, such as waterhyacinths, this presents a serious shortcoming.
One example of such a slow-moving vehicle is the RETADOR, model P-140, available through SORE CIA Constructora Hidalgo, S.A. de C.V., Autopista Mexico-Queretaro No. 2222-3 er. Piso-Colonia Valle Verde, Tlalnepantla, Estado de Mexico-C.P. 54040 (tel. 398-78-55 or 398-78-66). This machine is a tractor-like vehicle having a 140 h.p. diesel engine. According to the manufacturer's brochure describing the RETADOR, the machine travels at an average speed of 1.24 miles/hour while clearing water lilies at a maximum density of 176.4 lb/10.764 square feet. A shredding capacity of 1.97 acres/hour, equivalent to 705.28 tons per hour, the RETADOR sits on floaters, or pontoons, and is propelled by revolving paddle wheels mounted on each side of the machine. The machine is equipped with cutting blades mounted by means of hydraulic jacks at the bow end of the boat.
Waterhyacinths are aquatic weeds that can double in surface area in 7 days during their growing season, growing to a density in some areas of up to 200 tons per acre. Since these plants are approximately 95% water, handling and removal of this biomass is expensive. In Florida, where waterhyacinth infestation has become a major problem in the waterways, control by chemical means has been attempted. This requires constant maintenance and potential toxicity to fish and other wildlife. See the publication of the Bureau of Aquatic Plant Management, Technical Services Section, 3917 Commonwealth Boulevard, Tallahassee, Fla. 32399, tel. 904-487-2600, entitled: "Weed Alert! Waterhyacinth (Eichhornia crassipes)." The cost of controlling waterhyacinth in Florida alone is estimated at $2.5 million annually. Cost estimates for different types of weeds and methods of control are as follows, using 1985 dollar values:
TABLE 1 ______________________________________ Average aquatic weed control costs per acre for mechanical and herbicide control of floating and submersed vegetation. Cost estimates based on expenditures reported to the DNR and reported in the literature. Targeted Location Average Costs Type of Weed Weed of Weed per Acre Using Control Species Control 1985 Dollars.sup.a ______________________________________ Large mechanical Hydrilla Florida $733.00.sup.b harvester Large mechanical Water- Florida $4,649.00.sup.c harvester hyacinth Large mechanical Eurasian Northeast $301.00.sup.d harvester watermilfoil United States Herbicide Hydrilla Florida $288.00.sup.e Herbicide Water- Florida $60.00.sup.e hyacinth ______________________________________ .sup.a Estimated using the Industrial Commodities Producer Price Index, Bureau of Labor Statistics, United States Department of Labor. .sup.b Average per acre cost based on 24 Florida locations. .sup.c Average per acre cost based on 23 Florida locations. .sup.d Average per acre cost based on 6 NE United States locations. .sup.e Average per acre cost based on statewide expenditures reported to the Florida Department of Natural Resources.
Accordingly, there remains a pressing need for more efficient means for controlling infestation of water bodies by waterhyacinths and other weeds.
In the present invention, the limitations of known water craft and the problems associated with chemical control of aquatic weeds are overcome by a new water craft that efficiently removes plant infestation.